Augustine Pulu leads the charge at the Blues; his destructive running game and penchant for punishing hits regularly capturing attention. Such abrasive qualities lend him to offering the All Blacks major impact off the bench, and potentially the chance to add to his two tests in 2014.
Brad Weber, who played one test against Samoa in 2015, is due to return from a broken leg with Hawke's Bay in the Mitre 10 Cup. Weber, a nuggety halfback, possesses a crisp pass and pace to the breakdown.
At the Crusaders Bryn Hall's speed to ruck and support play has impressed at times and what Mitchell Drummond, Hall's job-sharing partner, lacks in the sniping department he makes up for as one of New Zealand's cleanest passers.
Despite his indifferent performance against the British and Irish Lions, young Hurricanes and Taranaki halfback Te Toiroa Tahuriorangi remains in the frame, though being stuck behind TJ Perenara doesn't help his case.
And Canterbury's New Zealand under-20s prospect Ereatara Enari is considered a longer term contender.
But barring injury Aaron Smith, Perenara and Kerr-Barlow are likely to be locked in for the rest of the year. The onus is on one from above to smash down the selection door and force a change in thinking.
Kerr-Barlow's strength lies in his ability to give the national team a point of difference. The All Blacks don't want three identical halfbacks. They want different styles capable of altering the way they play. This is why Pulu is probably the biggest threat to the La Rochelle-bound Kerr-Barlow.
The 37-man squad the All Blacks plan to take on the end of season tour, combined with a match against the Barbarians and mid-week fixture in France, present opportunities to blood new players. It's here the likes of Blues prop Ofa Tu'ungafasi and Highlanders playmaker Lima Sopoaga can expect starting chances in the absence of Faumuina and Cruden.
In theory it would make sense to take the next halfback contender on this journey, too. But he must earn his place. In this influential area, the All Blacks remain intent on selecting the best available contenders, regardless of future commitments.